17 Must Haves When Building An Energy Efficient Home
Why build an energy-efficient home? The answer is convincing. An energy-efficient home saves money by reducing energy use, provides a higher level of comfort to its occupants and increases the resale value of the house. Energy-efficient homes also fight against increasing greenhouse gases and global warming. Negative impacts of global warming include rising sea levels due to growing rates of glacial melting, more acidic oceans due to climbing carbon dioxide levels, and more frequent and severe weather events. Fortunately, recent technological advancements in building materials and construction techniques make the process of building an energy-efficient home less challenging. New home builders have many decisions to make when building an energy-efficient home; however, most energy-efficient homes have several things in common. An energy-efficient home has a tightly sealed thermal envelope, controlled ventilation, high-efficiency heating and cooling systems, and energy-efficient doors, windows, appliances, and home electronics. The ultimate goal of an energy-efficient home is to achieve net zero energy use and create a comfortable home with high indoor environmental quality.
1. A Whole-Building System Approach for Designing an Energy-Efficient Home
The whole-building system approach treats a home as one energy system in which each part affects the performance of the whole-house. The whole-building system approach makes efficient use of water, electricity and other natural resources and strives to minimize waste and materials. It also ensures that all the building professionals are informed and understand every aspects that affect energy use in the home. The goal of the whole-building system approach is to create a home with lower utility and maintenance costs, improved durability and comfort, and a healthy and safe indoor environment. Architects, contractors, and homeowners agree that designing an energy-efficient home requires a whole-building system approach.
2. Site and Room Orientation of an Energy-Efficient Home
Proper site orientation (passive solar design) of a home is essential for taking advantage of the sun’s energy. Specifically, in the Northern Hemisphere homes should be oriented north-south. The north-south orientation minimizes direct sunlight during the summer (which lessens cooling demands) while maximizing sunlight during the winter (which lessons heating demands).
Room orientation is also an important design consideration of an energy-efficient home.
South facing rooms have good sun most of the day and are ideal for the main living spaces like living, family, and dining rooms.
East facing rooms have good sun during the morning and are cool in the late afternoon, which is great for kitchens and bedrooms.
West facing rooms get the late afternoon sun, which can be a problem for kitchens and bedrooms.
North facing rooms have low levels of sunlight and are best suited for service areas such as garages, laundries and bathrooms.
3. Thermal Mass Materials of an Energy-Efficient Home
High thermal mass materials are an important design element of an energy-efficient home and typically used in walls and slab foundations. Thermal mass is the potential of a material to absorb and store heat energy. High thermal mass materials help stabilize temperature shifts within a home by slowing the rate of heat transfer. For example, at night an insulated concrete wall and floor will absorb the cool air and store it within its mass. During the day, if the walls and floors are shaded, they will stay cool and so will the interior of the home. In the winter, during daylight, the concrete walls and floors absorbs the sun's heat energy. During the night, the heat then slowly spreads through the wall and floor (conductivity) and releases into the home. Water, stone, brick, and concrete are examples of materials with high thermal mass. Steel, wood, and carpeting are examples of materials with low thermal mass and should be avoided as part of an energy-efficient home design.
4. Continuous Insulation of an Energy-Efficient Home
An essential design component of an energy-efficient home is continuous insulation (CI). In fact, the ASHRAE 90.1 and the International Energy Conservation Code (2015 IECC) require continuous insulation, which is defined by the ASHRAE Standard 90.1-2013 as insulation that is uncompressed and continuous across all structural members without thermal bridges other than fasteners and service openings. A thermal bridge is a section of a wall assembly that allows heat and energy to flow through it at a higher rate than the surrounding area and reduces the effective R-value1 of the wall assembly. The purpose of CI is to stop thermal bridging, increase the effective R-value\ and eliminate condensation. Continuous insulation stops air leakage (thermal bridging) in a home and saves homeowners money and energy by reducing mechanical ventilation costs and heating and cooling expenses.
5. Air and Moisture Barrier of an Energy-Efficient Home
Preventing air and moisture infiltration to the interior of a house is essential to the design of an energy-efficient home. Air tightness of a home is a critical factor in eliminating thermal bridges. Moisture resistance is crucial to preventing rot and the growth of mold and mildew, which can significantly degrade the indoor environmental quality of a home. To minimize air and moisture infiltration within a home, an air and moisture barrier, along with continuous insulation, is imperative to an energy-efficient home design.
A cool roof of an energy-efficient home protects against solar heat gain and keeps the house and attic space cool. Asphalt shingles, a traditional roofing material, has a high thermal mass and will absorb the sun’s heat, which will transfer to the inside of a home. Typically, a cool roof is made of low thermal mass materials like tiles, slate, or clay that are reflective or have light colored pigments that reflect the sunlight. A wonderful cool roof option for homes with flat rooftops and limited green space, is a green roof. Green roofs include anything from simple plant cover to a working garden. Cool roofs improve indoor comfort and reduce energy bills. They can also extend the roof’s service life.
8. Insulated and Waterproof Slab Foundation of an Energy-Efficient Home
Slab foundations are most effective way to separate an energy-efficient home from the ground; saving time, money, and materials. Concrete slabs, along with a continuous layer of rigid foam insulation under the slab, are perfect for an energy-efficient home design. The high thermal mass of concrete holds radiant energy and keeps a home warm and dry inside. Also, an acid-etched or dyed concrete slab is a very attractive finished floor.
9. The Heating and Cooling System of an Energy-Efficient Home
A home’s heating and cooling system account for 48 percent of a home’s energy use. The design of an energy-efficient home should consider high-efficiency heating and cooling systems that use less energy. For example, the most efficient HVAC system is 95 percent efficient; meaning 5 percent of the energy produced is lost. It is imperative that HVAC professionals install the systems in accordance with ENERGY STAR homes. Improper installation of an HVAC lessens the efficiency of a system by up to 30 percent. VRF and variable speed HVAC systems are some of the most efficient systems available.
10. Ventilation of an Energy-Efficient Home
Controlling ventilation of an energy-efficient home is critical because the air-tightness of an energy-efficient home may trap pollutants (like radon, formaldehyde, and volatile organic compounds). It is essential for an energy-efficient home to install an energy recovery ventilation system. An energy recovery ventilation system controls ventilation and minimizes energy loss by transferring energy from conditioned air going out to fresh incoming air. Other useful methods of ventilation for an energy-efficient home are spot ventilation, such as exhaust fans in the kitchen and bathrooms, along with natural ventilation.
11. Glazing System of an Energy-Efficient Home
The windows, skylights and doors of an energy efficient home provide light, warmth, ventilation, along with energy and cost savings. Design of an energy-efficient home should include energy efficient windows, skylights, and doors appropriate to the home’s climate zone. Also, in the northern hemisphere, major glazing areas should face south to take advantage of the sun’s energy in winter months when the sun is low. For warmer climates, limit south facing windows. If windows face south, install shading devices can prevents excessive heat gain during the hot, summer months.
12. Energy-Efficient Appliances
Design of an energy-efficient home includes energy-efficient appliances: washer and dryer, refrigerator, dishwasher, microwave, dehumidifier, freezer, etc. Energy-efficient appliances reduce a home's energy use, emit less air pollution and increase the resale value of a home. Selecting ENERGY STAR appliances ensure the product saves energy and money and protects the environment.
Lighting contributes up to 15% of a home’s annual electricity costs and is a crucial design consideration of an energy-efficient home. Controls such as timers, photocells that turn lights off when not in use and dimmers can save money and energy. Examples of energy-efficient lighting include light-emitting diodes (LEDs), compact fluorescent lamps (CFLs), and halogen incandescent.
Light emitting diodes (LEDs) bulbs contain semiconductors diodes that convert electricity into light. LEDs are often used in recessed fixtures, and small track lights, desk lamps, kitchen, under cabinet lighting, and outdoors. LEDs are about 90 percent more efficient than incandescent light bulbs; however they are expensive, ranging from about $10 to $40. LEDs are the longest lasting energy-efficient bulb. LEDs last 50 times longer than a incandescent, 20-25 times longer than a halogen, and 8-10 times longer than a CFL.
Compact fluorescent lamps are compact fluorescent light bulbs often used in recessed or can lighting. They cost between $1.25 and $2.50 for a 60-watt-equivalent bulb. The CFL bulb burns cool and uses much less energy than a traditional incandescent bulb. However, the cons of the CFL is it may take a minute or more to reach full brightness and CFLs contain a small amount of mercury, which makes recycling difficult.
Halogen incandescents have a capsule inside that holds gas around a filament to increase bulb efficiency. They are are similar to traditional incandescent bulbs, but use less electricity. Halogen are the least expensive energy-efficient lighting option at less than $1 each; however, they do not have the longevity of LED and some of CFL bulbs.
16. Energy-Efficient Home Design Includes Smart Home Devices
Including smarthome products in the design of an energy-efficient home is a convenient option for a homeowner that saves money and energy and makes a home safer. Examples of smart home products include programmable thermostats, occupancy or motion sensors, CO2 and other air quality alarms.
17. Renewable Energy Sources of an Energy-Efficient Home
The ultimate goal of an energy-efficient home is to achieve net zero energy use. The design should also strive to meet the Energy Star requirements for sustainability, the Leadership in Energy and Environmental Design (LEED) standards, and the International Green Construction Code (IgCC). Achieving these standards and requirements will create an energy-efficient home that saves money and energy, creates a high degree of comfort for the occupants, and ultimately increase the resale value of the house. Visit Bautex Wall System for more information on must have elements for designing an energy-efficient home.
A building's wall assembly resistance to this flow is measured by its effective R-value. The effective R-value includes all the materials used in its construction: the studs, siding, drywall, fiberglass batts, plywood or OSB sheathing, water control plane. The higher the R-value, the less the conductivities of the wall assembly.